Updated: Jul 28, 2021
“We contain the shapes of trees and the movement of rivers and stars within us.” – Patrick Jasper Lee
When trying to understand autism we typically look at the social, communication and more recently the sensory differences experienced by autistic people, but the word neurodiversity was coined for a reason, autistic people think differently too. In this article we will look more closely at how 2 types of long-term memory, the episodic memory and the semantic memory work differently in autistic people and how a better understanding of these types of memories can help autistic people to function more effectively in the world.
Our memory is a complex process and one that we do not yet fully understand. In our current model of memory, sensory information enters the body through our sense organs and is available as a sensory memory for up to 3 seconds in a typical individual, this allows us to choose what information we want to attend to and information we feel deserves our attention is then passed to the short term memory where it can be held for about 20-30 seconds, from here relevant information is passed to the long term memory for storage and later retrieval. Our long-term memory is divided further into explicit memories which can consciously be recalled and implicit memories which are largely unconscious. Both episodic and semantic memories are types of explicit memories. Autistic people can experience differences in all aspects of memory and while this is a fascinating subject, for simplicity I will focus only on episodic and semantic memory for today.
Episodic memory is better understood if we think of it as our autobiographical memory. It enables us to have a consistent sense of ourselves over time and kicks in not only when recalling past experiences but also when planning for the future. When we make plans for the future, we reflect on what our past experiences have been and use these experiences to inform decision making. We are able to do this thanks to our episodic memory. Now episodic memory is not a strength for autistic people and for some people it can make it difficult to recall what has been done on a previous day and to accurately attend to the passage of time. This is not the case for all autistic people but many will have difficulties with planning which are in part due to episodic memory difficulties. Episodic memory has another important role in that it helps us to have a consistent sense of self. If we cannot recall our feelings about past events it will be difficult to recognize experiences we enjoy, what we want to avoid and the things that are important to us. One explanation for why episodic memory is an area of weakness for autistic people is to consider it as a multi sensory process which requires us to process both internal and external sensations simultaneously. Try to recall now a happy memory you have for example visiting a restaurant with some friends, there will likely be many aspects to this memory including the taste of the food, what your friends said, the music you heard, what you saw as well as internal sensations such as how much energy you had and your emotional response to the experience. When you put all this information together you have facts embedded in context for example ‘I ate a pizza, I enjoyed the pizza but didn’t eat much as I wasn’t very hungry’. This context gives us important information for planning for example ‘I will order the pizza again, but I will make sure I am hungry next time I go’. Many autistic people experience sensory sensitivities which can make sensory experiences (e.g. life) feel overwhelming and lead to difficulties in deciding what information to pay attention to. One adaptation to cope with this experience is mono-processing which is the process of paying attention to one sense at a time rather than multiple senses simultaneously. This can prevent sensory overload, but it can also lead to the context of the experience being missed. For example, if you taste the pizza without at the same time paying attention to your emotional reaction you will have no way or knowing if you like the pizza. Another example would be to listen to your friends voice without looking at their facial expressions which could cause you to miss the meaning behind the words being said.
Now whilst autistic people may have difficulties with episodic memory, semantic memory is where they really come into their own. Many autistic people will have high IQ’s and powerful reasoning abilities due to the strength of their semantic memories. Semantic memory is our ability to record facts and figures about the world. People with strong semantic memories will be good at spotting patterns and figuring out how things work. This is why there are a disproportionately high proportion of autistic people working in fields such as mathematics, science and technology where remembering facts and figuring out how things work is important. Strong sematic memory can also aid in creating beautiful things such as music and art which are reliant on an understanding of rhythm and patterns. Many people believe that both Andy Warhol and Wolfgang Mozart were autistic. So why is semantic memory so strong in autistic people? It is possible that it is a compensatory strategy that was developed in early childhood. Autistic children who experience difficultly interpreting events in the multi sensory way required to develop contextual episodic memory may have to rely more heavily on their semantic memory to navigate and make sense of the world. The expression ‘use it or lose it’ describes how the pathways and areas in our brain that we use the most particularly in young childhood will grow stronger whereas those that are used least will become weaker. This may explain why many autistic people with episodic memory difficulties have strong semantic memories.
Building on Strengths and Weaknesses
We all need to spend time working on our weaknesses to function successfully in this world whilst also building up our strengths as these are the areas where we will be able to contribute to the world and experience personal satisfaction. Some studies have suggested that visual cues can help autistic people to access and build strengths in episodic memory. Looking at photos of past events for example might help to trigger personal memories and help to develop a sense of the self being consistent over time. Videos have also been shown to be powerful tools in both teaching new skills to autistic people and in recalling important past events, what happened and how they felt about them. Autistic people will often use the strength of their semantic memory to help them to learn social rules and navigate in situations where non-autistic people would rely more on their episodic memory. Therefore using teaching methods such as social stories or role play can be important tools to aid recall of what to do when faced with similar situations in the future.
Neurodiversity is a wonderful thing, and the world would be a much poorer place if we all thought and experienced the world the same. Understanding how autistic people think differently not only helps autistic people to function successfully in the world but also helps non-autistic people to benefit from the gifts that the neurodivergent have to offer the world.